Process and apparatus for removing a layer of fluid on top of a bath

Abstract

In the removal of a layer of fluid located on a bath, such as a layer of reaction products in pyrometallurgical crude-lead refining, the layer is propelled by an agitating mechanism into the intake of a stationary conveyor. The conveyor removes the layer of fluid through a trough from the bath.

We claim: 
     
       1. Apparatus for the removal of a slag layer floating on the surface of a melt, such as the removal of a slag layer from the surface of a lead melt during refining, comprising a melting vessel, and an axially elongated mechanical screw conveyor located within said vessel and extending into the slag layer, wherein the improvement comprises that said screw conveyor has a first axially extending stage located within said melting vessel and a second axially extending stage located outside of said melting vessel, a closed housing enclosing said first and second stages of said screw conveyor and having a stepped bottom, said stepped bottom comprises a lower stage located within said melting vessel and enclosing said first stage of said screw conveyor and an upper stage spaced upwardly from said lower stage and located outside of said melting vessel and enclosing said second stage of said screw conveyor, an inlet opening located in and extending in the axial direction of said lower stage of said housing, an outlet opening located in the bottom of the upper stage of said housing spaced outwardly from said lower stage, and said inlet opening arranged to be located within the slag layer so that said first stage of said screw conveyor removes the slag and conveys the slag to the outlet opening. 
     
     
       2. Apparatus, as set forth in claim 1, wherein said screw conveyor extends horizontally within said housing, and lifting rams mounted on said housing for moving said housing and screw conveyor in the vertical direction. 
     
     
       3. An apparatus, as set forth in claim 1 or 2, wherein said conveyor is movable over the surface of the melt in said melting vessel. 
     
     
       4. Apparatus, as set forth in claim 1, wherein said first stage of said screw conveyor has a larger diameter than said second stage of said screw conveyor and said first and second stages being disposed in axial alignment. 
     
     
       5. Apparatus, as set forth in claim 1, including a cover hood positioned over said melting vessel and extending over said housing for said screw conveyor at least in the region above said melting vessel. 
     
     
       6. Apparatus, as set forth in claim 6, wherein a suction unit is mounted on said cover hood and communicates with the space under said cover hood. 
     
     
       7. Apparatus, as set forth in claim 1, wherein said screw conveyor includes a transition stage interconnecting said first stage and said second stage, and said housing comprises an intermediate stage located between and interconnecting said lower stage and said upper stage.